Process for the distillation of zinc and similar metals



Patented May 7,1935

PATENT worries fifiiwdil PROCESS FOR THE DKSTELATKGN F 39 AND SUVMJARMETrkL Arthur Leysner, hiagdeburg, Germany, assignor to the firm Fried.Krupp Grusonwerk Aktiengeselischait, lviagdeburg-Buckau, Germany NoDrawing. Application September'fi, 1e33, Serial No. $238,414. In GermanySeptember 23,

i mere. 7 an. 25-28) The'p'resent invention relates to the distillationof zinc and similar metals, wherein it is known that nickel and cobaltin a finely divided state, especially as metallic sponge, act as cata- &lysts in reduction processes, the action beingiapparently due to thefact that, in the presence of these metals, the ratio of CO to C02 isaltered in 'favour oi CO. In the distillation of zinc, cadmium andsimilar easily volatilizable metals, it is of decisive importance thatthe carbonic acid content of the gases should be kept as low aspossible, because otherwise, the metallic vapours that are formed beingimmediately oxidized in an atmosphere of such gases, an excessiveformation of dross takes place on the condensation of v these metallicvapours. It has been found by experiment that, instead of nickel spongeor cobait sponge, the pure metalsor alloys of these metals can be usedwith very good results, not as sponge,.but in a compact form, and it isone of the objects of the present invention to facilitate the use ofsuch metals or alloys in this form.

According to the invention, the reduction chamher or vessel itself ismade of the pure metals or of their alloys-e. g., of anickel-chromium-iron alloy. 'In processes known hitherto, a gas suitablefor the condensation operation can be produced only when the reductiontemperature in the muflle is kept relatively high. The essential 0technical advance in the employment of reduction chambers or vesselsaccording to this inven- Q tion, which act catalytically onthe,composition metals.

of the .gas, lies in the fact that a gas well suited for thecondensation process can be obtained even at considerably lowertemperatures. For example, when using a mums as hitherto known for thedistillation of zinc at 1100"v C., there is obtained a gaseous mixtureof CO and (302 with about 4 to 5% 002, while at the same temperature, bythe use of a muflie whose inner surface consists oi nickel, cobalt ortheir alloys a gas with less than 1% CO2 is produced. Intheseexperiments, no alteration of the surface of the metal chambers orvessels could be detected, from which it is to be concluded that theaction on the gasesis a catalytic one. I

The process is of especial advantage in the employment of rotatingmuflles; this advantage may be attributed to the fact that,-in thiscase, the vessel wall which acts as a catalyst comes alternately intocontact with the reduction gases and with the charge that is mixed withcarbon, so

that the catalyst is kept especially reactive.

What I claim is:-- The process of recovering volatilizable metals byreduction of materials containing them, which comprises heating thematerials in a rotary muflle,

the walls 'of which are composed at least partly of one or both of themetals riickel and cobalt, while maintaining in the mufile an atmospherecomposed principally of carbon monoxide, in order to reduce thematerials and volatilize the ARTHUR LEYSNER.

